Archive for the ‘Science Lesson’ Category

Italian motorcyclist Luca Colombo rode across Italy’s third largest lake, Lago di Como, on a modded Suzuki RMZ 450. The video has been blowing minds all over the internet, but anybody who has watched motocross movies has seen riders glide their way at least partly across a body of water. It’s just a matter of physics and something we encounter on a rainy day.

The phenomenon is known as hydroplaning or aquaplaning (depending on which continent you’re on). Most of us know it from that scary moment while driving when the car starts to slide on a wet road. What’s happening is that the speed at which the car is traveling creates pressure under the tires. At a certain point (NASA calculated an equation for this in 1963 but the speed is in knots), the pressure under the tires equals—and eventually exceeds—the weight of your car, lifting it off the road. As there’s less friction between your car and the water, you end up feeling like you’re sliding.

The same thing happens when motorcyclists glide across a pond. A bike’s light weight may make the feat seem easy, but narrow tires cause the weight to be distributed across a smaller area, making it more likely to sink. Plus since a rider is intentionally hydroplaning, they also have to consider the transition from land to water.

Luca had some help to keep his Suzuki afloat. You can see ski-like blades attached to the wheels, which increase the area of distribution of weight. The back tire also has treads designed to push him across the surface of the lake.

A couple weeks ago, I attended the ConTex Kickoff Brunch. It was mostly an introduction to the program, which aims to study mild, sports-related traumatic brain injury in patients ages 12-20 and get an idea of how TBI is being treated in the Dallas-Fort Worth Metroplex. I was able to get some important information that I didn’t cover in a previous post about TBI in relation to action sports.

There I am in the blue and green shirt. Photo from UTSW Dept of Neurology and Neurotherapeutics

There’s between 1.6 and 3.8 million reported concussions every year. Many experts believe that there is a significant amount of under-reporting due to lack of knowledge of symptoms (you don’t have to lose consciousness and CAT scans can be negative) and a strong desire to not get sidelined, whether you’re playing football or skating. Much of the focus has been on football because that’s where the funding comes from and it is America’s beloved pastime. However, you can get a concussion from any sport so it’s important to have safe practices and be aware, regardless of what you’re doing.

Women actually have an increase incidence of concussion. Some of it is due to more reporting, and some of it is due to head size and neck strength. Thus even if the female athletes are doing fewer spins at a lower height, the risk they face is nothing to overlook.

So what can the action sports community do? (That was a question I asked.) Learn about concussions and its various symptoms. Have our friends and family study them up too. Go to your annual physicals so that you and your doctor have an idea of what is “normal” for you; that will allow them to spot something out of the ordinary that could be a long-term side effect.

Football players have the Maddocks Questions to check up on an athlete who has been hit. I propose an action sports version:
1. What’s the name of the park?
2. What trick were you doing?
3. What’s the last trick you landed?
4. Who are you skating/riding with?
5. [for contests] Who’s in the lead?

Although there have been interesting developments in TBI research related to biomarkers (proteins that the body produces in response to a concussion) and genetics, lack of resources and funding have produced a need for better statistics on injured groups and long-term studies. We have no idea why some people develop chronic traumatic encephalopathy (degeneration of the brain) and others don’t. Moreover, a lot of the focus remains on treatment rather than prevention. This is why it’s important for everybody to do their part in staying safe. Even though action sports has prided itself on pushing forward against all odds, sometimes it’s better to sit out.

This past spring, Mat Hoffman told the story of how in 1999, he tore his ACL underwent surgery without anesthesia to receive a synthetic ligament. Because the LARS™ ligament was banned in the U.S., he had to go to Canada. The video, illustrated by Taj Mihelic, described why there was no anesthesia and what made it so revolutionary for him. It piqued my interest in the LARS™ ligament so I did a little digging about its history and current studies.

The Ligament Advanced Reinforcement System, or LARS™, was developed in 1992 with hopes of solving problems with synthetic ligaments in the past decade (Corin). Those often failed or caused inflammation in the synovial membrane that lines the joints (Machotka et al. 2010). The LARS™ ligament was made from terephthalic polyethylene polyester fibers that are twisted for increased durability.

From Corin

When Mat received his LARS™ ligament, the procedure was still relatively new. It made headlines in Australia around 2010, as more professional athletes got LARS™ ligaments and enjoyed the speedy recovery. That’s not to say there weren’t critics. Moreover, the FDA has yet to approve it.

Reviews of clinical studies thus far lean towards positive outcomes. Batty et al. and Chen at al. have compared the efficacy of many types of synthetic ligaments, and the LARS ligament produced the lowest rate of failure. The results reinforces the idea that this could be a solution to the severe side effects experienced with its predecessors. One issue appears to be the long-term durability. A study by Tiefenboeck et al. published this year examined patients who had their ACL reconstructed with the ligament with at least a ten-year follow-up reveals that re-rupturing does occur. They do not recommend the LARS™ ligament for primary ACL reconstruction. This is, however, just one study. As more results are published and more patients are observed in the long run, a better idea of the uses and limitations of the LARS™ ligament will be known. In Mat’s case, it appears to be a great success.
References

Last year, I wrote a post about the physics behind a triple backflip in BMX. Well, as most of you know by now, Josh Sheehan has done a triple backflip on a dirt bike. If you haven’t seen the video, here it is:

Now that he’s done what we had thought would be the impossible (though we said that about the double before Travis did it), that leaves us with the question of whether there is a limit. Buzz Skyline did some calculations at his blog, eXtreme Sports Physics, and came up with a total of four flips.

Another physics blog, Physics Buzz, took a look at the front flip. While a backflip has the rider utilizing the bike’s natural momentum and the ramp’s angle (which shaves off half of the first rotation), a front flip combats those forces AND the landing is blind. As Jim DeChamp told ESPN, “[I]t’s not a natural beauty trick— it’s like, that is awkward, that is wrong.” The Physics Buzz post looks at both what happens when a front flip is executed properly and when things go wrong.

I’m pretty sure we’re not going to see a triple backflip in the X Games. The ramps just aren’t big enough. Who knows about the double backflip or the front flip, but my guess is that the new Quarterpipe event is going to take riders in the direction of off-axis flips and 360s. We’ll see.

“Where’s my hoverboard?” is something I often hear when people complain about things we should have already by now. It’s become more common now that it’s 2015, the year in which Back to the Future Part II takes place. Fear not, science has not completely broken its promise.

Last November, a video of Tony Hawk riding a Hendo Hoverboard prototype on a halfpipe surfaced.
I found the accompanying RIDE Channel article, which piqued my interest in the science behind the hoverboard. Although it brought up magnetic repulsion, the Hendo Hoverboard Kickstarter revealed that the physics are a bit complicated. After all, it’s nearly impossible to levitate one magnet on top of another without special conditions.

That’s also true for the Hendo Hoverboard, which is why it’s not quite ready for every day use. The board contains four magnetic engines. They generate eddy currents, which create a magnetic field in opposition to the field created by the engine. The opposing forces causes the board to be repelled by the surface. This is called Lenz’s law. Check out a smaller, more up-close example of how the engines work:

One big caveat to the hoverboard is the surface you ride on has to be made of a non-ferrous (does not contain iron) conductor. Therefore, you can’t ride it outside of the Arx Pax or a hypothetical “hoverpark”. Another issue, as seen with Tony Hawk’s ride, is control of the direction of travel. Despite having pressure-sensitive pads on the deck, the lack of friction makes it hard to figure out how much pressure to apply. It seems to be extra sensitive. Lastly, the biggest issue is that for now, we can only ride it for a few minutes before the battery runs out.

So we’re going to have to wait a bit before we all fly around on hoverboards. However, the idea of one has already made its way into reality. Moreover, we can take comfort in knowing that there are some things from Back to the Future Part II that did come true in a way.

This weekend, I discovered a show on The Science Channel called Outrageous Acts of Science. It provides a snappy explanation behind the viral videos that have been collected based on a scientific topic. Think Ridiculousness with scientists and engineers.

That’s why it shouldn’t have been a surprise that triple backflipping BMX rider Jed Mildon made it into the show. Physics has never been my forte so I’ll let the video do the talking. Plus you get to hear Jed’s point of view juxtaposed with explanations by the show’s experts. It really gives an overall picture of what it takes to complete such a feat.

This isn’t the first time physics has taken an interest in Jed’s video. Three years ago, Wired had an article explaining why no one had ever done a triple flip before (and why you still don’t see them today). Click here to check it out.

I had quite a few gripes about both the U.S. and Canadian coverage of Olympic snowboarding and freeskiing (and apparently my friends did as well). It highlighted the inequality that’s rampant in both action sports and media, but that’s a post for another day. Right now I want to focus on one of the good things that came out of this: the increased opportunity to explore the science behind skiing and snowboarding. This is a great way to get action sports fans interested in science and scientists interested in action sports.

NBC paired with the National Science Foundation to create a series videos exploring the Science and Engineering of the 2014 Winter Olympic Games. They’d done a similar series in 2010, but now they have gone past just a cursory coverage of sports, looking at halfpipe engineering and snow. There’s also the addition of slopestyle skiing.

If you’re subscribed to The New York Times, you can get access to their interactive stories, which break down gold medal-winning runs and the keys to success. They’re definitely worth checking out just for the composite photography. Those without a subscription can catch some of the videos on Hulu.

The blog Physics Buzz did a podcast about snowboarding. They explained the triple cork better than I ever did, and there’s a link to a post that breaks down the physics of one.

We can’t forget about the Paralympians, especially with the debut of boardcross this year. Live Scienceshared an article about the technology that helps these athletes do things their able-bodied peers can do. I want to take this time to congratulate Evan Strong for grabbing the first U.S. Paralympic gold in Sochi, being a part of the American sweep in men’s boardercross with Michael Shea and Keith Gabel, and making his way onto an upcoming Wheaties box:

Finally, I came across a surprising mention to snowboarding while listening to the linguistic podcast, A Way with Words. The term “wind down the windows” caught the attention of host Martha Barnette because it’s becoming a rather dated image (I remember winding down the windows in my dad’s old pick-up as a little kid). It’s been pretty cool seeing and hearing snowboarding and freeskiing pop up in the most unexpected places.

Recently the web has been buzzing about bioluminescent waves in San Diego. This isn’t their first appearance in So Cal, and it won’t be their last. While they may not be rare, they do give an Otherworldly touch to surf footage. Check out this video from Man’s Best Media:

What’s responsible for the neon blue glow? In the ocean, there are these tiny organisms called dinoflagellates. Neither plant nor animal, dinoflagellates are protists comprised of a single cell with two appendages called flagella that they whirl around to propel them across the surface of the ocean. In fact their name comes from the Greek word for “whirling” (dinos) and the Latin for “whip” (flagellum). The species of dinoflagellate that causes the bioluminescent waves in So Cal is Lingulodinium polyedrum.

Lingulodinium polyedrum at night. From Hastings lab

When a dinoflagellate population explodes as a result of increased nutrients in the water and optimized growing conditions, it causes an algal bloom, also known as a “red tide” for the color that it changes the water. Not all blooms are red nor are they associated with the tide. Algal blooms can deplete the oxygen in the water, and certain dinoflagellates produce neurotoxins that kill fish and end up in the shellfish we eat. L. polyedrum was found to contain toxins, but the fact that surfers and beach-goers have no effect from the being in the water suggests that the toxins are at a low concentration.

Bioluminescent dinoflagellates can produce short flashes of light or a sustained glow in response to being disturbed by waves, boats, or predators. When a dinoflagellate sense a disturbance along its cellular membrane, the pH inside the cell drops, causing particles called scintillons to trigger a chemical reaction that produces the bioluminescence. The blueish-white areas in the picture of L. polyedrum above are the scintillons emitting light (the red is from chlorophyll). The flashes of light are used to distracts creatures that feed on dinoflagellates and attracts the attention of bigger predators. Not a bad defense mechanism for a single-celled organism, right?

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